Flame retardant internally cured polyurethane foam having improved properties

Abstract

Flexible polyurethane foam prepared from foam forming compositions of a polyether polyol, an organic isocyanate compound, a blowing agent, and a curing agent of a melamine derivative in an amount effective to rapidly cure the resultant foam and improve the compression set properties of the foam, the amount of curing agent generally ranging from about 0.01 up to about 2 parts by weight based on 100 parts polyether polyol. Also, flame retardant polyether polyurethane foam prepared from foam forming components of a polyether polyol, an organic isocyanate compound, water, a liquid phosphorus ester in an amount of about 4 to 10 parts by weight and the curing agent in an amount of 0.4 to 2 parts by weight, each based on 100 parts by weight of the polyether polyol in the composition. The most preferred curing agent has the formula C.sub.3 N.sub.6 (R.sub.2).sub.x (R.sub.1).sub.6-x wherein R 1 is hydrogen or an alkyl, alkenyl, cycloaliphatic or aryl moeity having between one and twelve carbon atoms; R 2 is an alkyl, alkenyl, cycloaliphatic or aryl moeity having between one and twelve carbon atoms and at least one hydroxyl moeity; and x is between about 0.5 and 6.

What is claimed is: 
     
       1. A flexible polyether derived polyurethane foam forming composition comprising a polyether polyol, an organic isocyanate compound, water, and a curing agent of the formula   C.sub.3 N.sub.6 (R.sub.2).sub.x (R.sub.1).sub.6-x     wherein R 1  is hydrogen or an alkyl, alkenyl, cycloaliphatic or aryl moiety having between one and twelve carbon atoms; R 2  is an alkyl, alkenyl, cycloaliphatic or aryl moiety having between one and twelve carbon atoms and at least one hydroxyl moiety; and x is between about 0.5 and 6, which curing agent is substantially non-reactive with the foam forming components but which acts as a catalyst to the reaction of remaining isocyanate groups with moisture in the foam after formation thereof, said curing agent added in an amount effective to cause the reaction of a sufficient number of said remaining isocyanate groups with said moisture to improve the compression set properties of the resulting flexible foam but less than about 2 parts by weight based on 100 parts by weight polyol.   
     
     
       2. The composition of claim 1 wherein the curing agent is used in an amount of between 0.01 and 1.4 parts by weight based on 100 parts by weight of the polyether polyol, and wherein the water is present in an amount of less than 6 parts by weight based on 100 parts by weight of the polyether polyol. 
     
     
       3. The composition of claim 1 wherein the amount of curing agent is between 0.4 and 1.4 parts by weight based on 100 parts by weight of the polyether polyol. 
     
     
       4. The composition of claim 1 wherein R 1  is hydrogen, R 2  is a hydroxy alkyl moiety having between 2 and 4 carbon atoms, and x is between 2 and 3, inclusive. 
     
     
       5. A flexible polyether derived polyurethane foam forming composition comprising a polyether polyol, an organic isocyanate compound, water, a liquid phosphorous ester in an amount sufficient to impart flame retardance to the resulting foam and a curing agent of the formula   C.sub.3 N.sub.6 (R.sub.2).sub.x (R.sub.1).sub.6-x     wherein R 1  is hydrogen or an alkyl, alkenyl, cycloaliphatic or aryl moeity having between one and twelve carbon atoms; R 2  is an alkyl, alkenyl, cycloaliphatic or aryl moeity having between one and twelve carbon atoms and at least one hydroxyl moeity; and x is between about 0.5 and 6, which curing agent is substantially non-reactive with the foam forming components but which acts as a catalyst to the reaction of remaining isocyanate groups with moisture in the foam after formation thereof, said curing agent added in an amount effective to cause the reaction of a sufficient number of said remaining isocyanate groups with said moisture to improve the compression set properties of the resulting flexible foam, but less than about 4 parts by weight based on 100 parts by weight polyol.   
     
     
       6. The composition of claim 5 wherein the amount of flame retardant agent ranges from about 4 to 8 parts. 
     
     
       7. The composition of claim 1 wherein the polyether polyol is a conventional, unmodified polyether polyol of a sufficient molecular weight and temperature so that the curing agent is at least partially soluble therein. 
     
     
       8. A flexible polyurethane foam formed from the foam-forming composition of any one of claims 1-7. 
     
     
       9. A method for rapidly curing and improving the compression set properties of a flexible polyether derived foam which comprises: adding to a polyurethane foam-forming composition containing a polyether polyol, an organic isocyanate compound, and water in an amount effective to act as a blowing agent, a curing agent of the formula   C.sub.3 N.sub.6 (R.sub.2).sub.x (R.sub.1).sub.6-x"     wherein R 1  is hydrogen or an alkyl, alkenyl, cycloaliphatic or aryl moiety having between one and twelve carbon atoms; R 2  is an alkyl, alkenyl, cycloaliphatic or aryl moiety having between one and twelve carbon atoms and at least one hydroxyl moiety; and x is between about 0.5 and 6, which curing agent is substantially non-reactive with the foam-forming components but which acts as a catalyst to the reaction of remaining isocyanate groups with moisture in the foam after formation thereof, said curing agent added in an amount effective to cause the rapid reaction of a sufficient number of said remaining isocyanate groups with said moisture to improve the compression set properties but less than about 2 parts by weight based on 100 parts by weight polyol; and     forming the polyurethane foam from said foam-forming composition, whereby said curing agent cures substantially all the resultant foam.   
     
     
       10. The method of claim 9 wherein the curing agent is present in an amount ranging from between about 0.01 and 1.4 parts by weight based on 100 parts by weight of the polyether polyol, and wherein the blowing agent is water in an amount of less than 6 parts by weight based on 100 parts by weight of the polyether polyol. 
     
     
       11. The method of claim 9 wherein the amount of curing agent ranges from between about 0.4 and 1.4 parts by weight based on 100 parts by weight of the polyether polyol. 
     
     
       12. The method of claim 9 wherein the polyether polyol is a conventional, unmodified polyether polyol of a sufficient molecular weight and temperature so that the curing agent can be at least partially solubilized therein. 
     
     
       13. The method of claim 12 wherein the curing agent and polyol are blended to form a mixture prior to being added to the remaining foam-forming components, wherein the amount of curing agent ranges between 25 and 50% by weight of said mixture. 
     
     
       14. The method of claim 9 wherein R 1  is hydrogen, R 2  is a hydroxy alkyl moiety having between 2 and 4 carbon atoms, and x is between 2 and 3, inclusive. 
     
     
       15. A method for maintaining the flame retardant properties of a flame retardant polyether polyurethane foam prepared from a polyurethane foam-forming composition comprising a polyether polyol, an organic isocyanate compound, water in an amount effective to act as a blowing agent, and a flame retardant additive which would normally be used in an amount of between 4 and 10 parts by weight based on 100 parts by weight of the polyether polyol, which method comprises: the replacing a minor portion of the amount of the flame retardant additive with an amount of a replacement compound of the formula   C.sub.3 N.sub.6 (R.sub.2).sub.x (R.sub.1).sub.6-x"     wherein R 1  is hydrogen or an alkyl, alkenyl, cycloaliphatic or aryl moiety having between one and twelve carbon atoms; R 2  is an alkyl, alkenyl, cycloaliphatic or aryl moiety having between one and twelve carbon atoms and at least one hydroxyl moiety; and x is between about 0.5 and 6, which amount of said compound is between about 20 and 200 percent of the minor portion of the additive to be replaced, said replacement amount being 4 parts by weight or less based on 100 parts by weight of the polyether polyol; and     thereafter forming the foam from the foam-forming composition to obtain a flexible foam having substantially the same flame retardance as one wherein a portion of the flame retardant additive is not replaced with the replacement compound.   
     
     
       16. The method of claim 15 wherein the minor portion of the flame retardant additive is an amount of less than about 33 weight percent of the total amount of the additive. 
     
     
       17. The method of claim 15 wherein the amount of replacement compound ranges from 50 to 100 percent of the minor portion of the flame retardant additive to be replaced, and wherein the minor portion of the flame retardant additive is an amount of less than about 25 weight percent of the total amount of the additive. 
     
     
       18. The method of claim 15 wherein the polyether polyol is a conventional, unmodified polyether polyol; the blowing agent is water in an amount of less than 6 parts by weight; the minor portion of the flame retardant additive ranges from between about 1 and 6 parts by weight; and the replacement amount of replacement compound is between about 0.2 and 2 parts by weight, said amounts all based on 100 parts by weight of the conventional, unmodified polyether polyol. 
     
     
       19. The method of claim 15 wherein the predetermined amount of the flame retardant ranges from between about 1 and 2 parts by weight and wherein the amount of the replacement compound is between about 0.4 and 1.4 parts by weight, said amounts based on 100 parts by weight polyol. 
     
     
       20. The method of claim 15 wherein the flame retardant additive is reactive with the isocyanate compound. 
     
     
       21. The flexible flame retardant polyether derived polyurethane foam formed by the method of any one of claims 9 to 20. 
     
     
       22. The composition of claim 1 wherein R 1  is hydrogen, R 2  has at least 2 carbon atoms and x is at least 2. 
     
     
       23. The method of claim 9 wherein R 1  is hydrogen, R 2  has at least 2 carbon atoms and x is at least 2. 
     
     
       24. The method of claim 15 wherein R 1  is hydrogen, R 2  has at least 2 carbon atoms and x is at least 2. 
     
     
       25. The method of claim 15 wherein the fire retardant additive is a liquid phosphorus ester compound. 
     
     
       26. The composition of claim 22 wherein the curing agent is present in an amount of about 1.4 parts or less. 
     
     
       27. The method of claim 23 wherein the curing agent is present in an amount of about 1.4 parts or less. 
     
     
       28. The method of claim 24 wherein the curing agent is present in an amount of about 1.4 parts or less. 
     
     
       29. The method of claim 15 wherein R 1  is hydrogen, R 2  is a hydroxyl alkyl moeity having between 2 and 4 carbon atoms, and x is between 2 and 3, inclusive. 
     
     
       30. A flexible polyether derived polyurethane foam forming composition comprising a polyether polyol, an organic isocyanate compound, water, a liquid phosphorus ester in an amount sufficient to impart flame retardance to the resulting foam and a curing agent of the formula   C.sub.3 N.sub.6 (R.sub.2).sub.x (R.sub.1).sub.6-x     wherein R 1  is hydrogen; R 2  is an isopropyl moeity; and x is between 1 and 3, which curing agent is substantially non-reactive with the foam forming components but which acts as a catalyst to the reaction of remaining isocyanate groups with moisture in the foam after formation thereof, said curing agent added in an amount effective to cause the reaction of a sufficient number of said remaining isocyanate groups with said moisture to improve the compression set properties of the resulting flexible foam, but less than about 2 parts by weight based on 100 parts by weight polyol.   
     
     
       31. A flexible polyether derived polyurethane foam forming composition comprising a polyether polyol, an organic isocyanate compound, water, a liquid phosphorus ester in an amount sufficient to impart flame retardance to the resulting foam and a curing agent of the formula   C.sub.3 N.sub.6 (R.sub.2).sub.x (R.sub.1).sub.6-x     wherein R 1  is hydrogen; R 2  is an isopropyl moeity; and x is between 1 and 3, which curing agent is substantially non-reactive with the foam forming components but which acts as a catalyst to the reaction of remaining isocyanate groups with moisture in the foam after formation thereof, said curing agent added in an amount effective to cause the reaction of a sufficient number of said remaining isocyanate groups with said moisture to improve the compression set properties of the resulting flexible foam, but less than about 4 parts by weight based on 100 parts by weight polyol.